Drive assemblies which utilize precessional torque of a gyroscopic mass are found in U.S. Pat. No. 3,495,479 of Feb. 17, 1970 to Rass and in U.S. Pat. No. 3,394,619 of July 30, 1968 to Preston. Both of these assemblies are rather complex and are difficult and expensive to implement. In Rass, the precessional torque is coupled out through a spring washer 66 which resists rotation of the flywheel element 61. The output torque is dependent upon the rotational speed of the input shaft. In Preston, a highly complex arrangement is employed in which cyclic coupling out of the torque is achieved.